GLYNN COUNTY, Ga. -- In day two of the trail of a South Georgia doctor accused of felony murder in the death of his roommate, experts shed more light on what exactly killed the 20-year-old.

Dr. Noel Chua, 45, was arrested in September 2006 on charges connected to the overdose death of his 20-year-old roommate, Jamie Carter III.

Carter was found slumped over a sink in Chua's home in December 2005.

Chua was charged with felony murder and 17 violations of Georgia's controlled substance act.

Friends and family members of Chua and of the victim packed the courtroom as medical experts detailed what medications were found in Carter's system.

One expert said he saw lethal levels of morphine, methadone and promethazine in Carter's blood.

"My determination within a reasonable degree of scientific certainty was that many of the drugs found by themselves or in combination was pulnonary edema, edema of the brain, lack of oxygen, and death due to central nervous system depression," a medical expert testified.

The court also got a look at a list of medicine found in Carter's system.

Prosecutors called several witnesses to the stand.

One expert said he was particularly concerned with what he considered lethal levels of two drugs -- morphine and methadone.

Defense attorneys contested it was unclear whether all the medications were prescribed by Chua or if Carter had his own methods of getting the meds.

Defense attorneys told Channel 4 they did not expect to call witnesses for a couple of days.

The Georgia Board of Medicine has revoked Chua's medical license. His office in St. Marys has remained closed since his arrest.